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中国物理学会期刊

快凝Pd82Si18合金原子团簇的演化特性及遗传机制

CSTR: 32037.14.aps.69.20190970

Evolution characteristics and hereditary mechanisms of clusters in rapidly solidified Pd82Si18 alloy

CSTR: 32037.14.aps.69.20190970
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  • 采用分子动力学(MD)模拟计算, 对Pd82Si18合金快凝过程中基本原子团簇的遗传特性、演化趋势和结构稳定性进行了研究. 团簇类型指数法(CTIM)分析表明: 非晶固体中Si原子为中心的(10 2/1441 8/1551)双帽阿基米德反棱柱(BSAP)团簇数目占据优势. 快凝过程中, BSAP结构团簇具有最大的遗传分数, 并且其他以Si原子为中心的Kasper团簇大多都会向BSAP结构团簇转变. 通过对Si原子为中心的Kasper基本团簇电子性质第一性原理计算发现, 体系中BSAP团簇的结合能最低, 结构稳定性较高, 与分子动力学计算结果一致.

     

    Molecular dynamics (MD) simulation and first-principles calculation were used to study the heredity characteristics, evolution trend and structural stability of basic clusters during the rapid solidification of Pd82Si18 alloy. The local atomic structures were characterized by the pair distribution function g(r) and the extended cluster-type index method (CTIM). The MD simulations reveal that the number of bi-cap Archimedes anti-prism (BSAP) clusters with CTIM index (10 2/1441 8/1551) is dominant in the amorphous solids rather than three-cap triangular prism(TTP) with CTIM index (9 3/1441 6/1551), which is identified be the most popular basic units in Pd82Si18 alloys analyzed by Voronoi index Relative to other basic clusters, the Si-centered BSAP possesses much larger fraction in the glassy state of Pd82Si18 alloys. Different from the findings in Cu-Zr alloys, the Si-centered BSAP instead of icosahedra has a larger hereditary fraction than any other Kasper clusters. During the solidification, it was found that most of the other Si-centered basic clusters are transferred into BSAP. Via the DFT calculations, it is observed that the Si-centered basic clusters with higher fraction of heredity and possesses lower binding energy. Among of them, BSAP always keeps lower binding energy than any other Si-centered Kasper clusters during the rapid solidification, resulting in its highest structural stability and the largest heredity fraction.

     

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